Four Earth-Sized Planets Detected Orbiting The Nearest Sun-Like Star

A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water.

The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second.

“We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets,” said coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.

According to lead author Fabo Feng of the University of Hertfordshire, UK, the researchers are getting tantalizingly close to the 10-centimeter-per-second limit required for detecting Earth analogs. “Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth’s habitability through comparison with these analogs,” Feng said. “We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals.”

The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.

The same team also investigated tau Ceti four years ago in 2013, when coauthor Mikko Tuomi of the University of Hertfordshire led an effort in developing data analysis techniques and using the star as a benchmark case. “We came up with an ingenious way of telling the difference between signals caused by planets and those caused by star’s activity. We realized that we could see how star’s activity differed at different wavelengths and use that information to separate this activity from signals of planets,” Tuomi said.

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals the team had identified in 2013 as planets. “But no matter how we look at the star, there seem to be at least four rocky planets orbiting it,” Tuomi said. “We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface. This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system.”

Sun-like stars are thought to be the best targets in the search for habitable Earth-like planets due to their similarity to the sun. Unlike more common smaller stars, such as the red dwarf stars Proxima Centauri and Trappist-1, they are not so faint that planets would be tidally locked, showing the same side to the star at all times. Tau Ceti is very similar to the sun in its size and brightness, and both stars host multi-planet systems.

The data were obtained by using the HARPS spectrograph (European Southern Observatory, Chile) and Keck-HIRES (W. M. Keck Observatory, Mauna Kea, Hawaii).

A paper on the new findings was accepted for publication in the Astronomical Journaland is available online. In addition to Vogt, Feng, and Tuomi, coauthors include Hugh Jones of the University of Hertfordshire, UK; John Barnes of the Open University, UK; Guillem Anglada-Escude of Queen Mary University of London; and Paul Butler of the Carnegie Institute of Washington.

Astrophysicists Predict Earth-Like Planet In Star System Only 16 Light Years Away

Astrophysicists at the University of Texas at Arlington have predicted that an Earth-like planet may be lurking in a star system just 16 light years away.

The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.

“According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth’s masses,” said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.

The astrophysicists published their findings this week as “Dynamics of a probable Earth-Like Planet in the GJ 832 System” in The Astrophysical Journal.

UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University’s commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.

“This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own,” Weiss said. “The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department’s astrophysics group.”

Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star — about 0.16 AU.

For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.

Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star — and so, measuring its velocity — one can see if it moves periodically due to the influence of a companion.

“We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system,” said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. “We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet,” the astrophysicist noted.

For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.

“The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis,” Satyal said. “At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system.”

Cosmic Magnifying Lens Reveals Inner Jets Of Black Holes

Astronomers using Caltech’s Owens Valley Radio Observatory (OVRO) have found evidence for a bizarre lensing system in space, in which a large assemblage of stars is magnifying a much more distant galaxy containing a jet-spewing supermassive black hole. The discovery provides the best view yet of blobs of hot gas that shoot out from supermassive black holes.

“We have known about the existence of these clumps of material streaming along black hole jets, and that they move close to the speed of light, but not much is known about their internal structure or how they are launched,” says Harish Vedantham, a Caltech Millikan Postdoctoral Scholar. “With lensing systems like this one, we can see the clumps closer to the central engine of the black hole and in much more detail than before.” Vedantham is lead author of two new studies describing the results in the Aug. 15 issue of The Astrophysical Journal. The international project is led by Anthony Readhead, the Robinson Professor of Astronomy, Emeritus, and director of the OVRO.

Many supermassive black holes at the centers of galaxies blast out jets of gas traveling near the speed of light. The gravity of black holes pulls material toward them, but some of that material ends up ejected away from the black hole in jets. The jets are active for one to 10 million years — every few years, they spit out additional clumps of hot material. With the new gravitational lensing system, these clumps can be seen at scales about 100 times smaller than before.

“The clumps we’re seeing are very close to the central black hole and are tiny — only a few light-days across. We think these tiny components moving at close to the speed of light are being magnified by a gravitational lens in the foreground spiral galaxy,” says Readhead. “This provides exquisite resolution of a millionth of a second of arc, which is equivalent to viewing a grain of salt on the moon from Earth.”

A critical element of this lensing system is the lens itself. The scientists think that this could be the first lens of intermediate mass — which means that it is bigger than previously observed “micro” lenses consisting of single stars and smaller than the well-studied massive lenses as big as galaxies. The lens described in the new paper, dubbed a “milli-lens,” is thought to be about 10,000 solar masses, and most likely consists of a cluster of stars. An advantage of a milli-sized lens is that it is small enough not to block the entire source, which allows the jet clumps to be magnified and viewed as they travel, one by one, behind the lens. What’s more, the researchers say the lens itself is of scientific interest because not much is known about objects of this intermediate-mass range.

“This system could provide a superb cosmic laboratory for both the study of gravitational milli-lensing and the inner workings of the nuclear jet in an active galaxy,” says Readhead.

The new findings are part of an OVRO program to obtain twice-weekly observations of 1,800 active supermassive black holes and their host galaxies, using OVRO’s 40-meter telescope, which detects radio emissions from celestial objects. The program has been running since 2008 in support of NASA’s Fermi mission, which observes the same galaxies in higher-energy gamma rays.

In 2010, the OVRO researchers noticed something unusual happening with the galaxy in the study, an active galaxy called PKS 1413+ 135. Its radio emission had brightened, faded, and then brightened again in a very symmetrical fashion over the course of a year. The same type of event happened again in 2015. After a careful analysis that ruled out other scenarios, the researchers concluded that the overall brightening of the galaxy is most likely due to two successive high-speed clumps ejected by the galaxy’s black hole a few years apart. The clumps traveled along the jet and became magnified when they passed behind the milli-lens.

“It has taken observations of a huge number of galaxies to find this one object with the symmetrical dips in brightness that point to the presence of a gravitational lens,” says coauthor Timothy Pearson, a senior research scientist at Caltech who helped discover in 1981 that the jet clumps travel at close to the speed of light. “We are now looking hard at all our other data to try to find similar objects that can give a magnified view of galactic nuclei.”

The next step to confirm the PKS 1413+ 135 results is to observe the galaxy with a technique called very-long-baseline interferometry (VLBI), in which radio telescopes across the globe work together to image cosmic objects in detail. The researchers plan to use this technique beginning this fall to look at the galaxy and its supermassive black hole, which is expected to shoot out another clump of jet material in the next few years. With the VLBI technique, they should be able to see the clump smeared out into an arc across the sky via the light-bending effects of the milli-lens. Identifying an arc would confirm that indeed a milli-lens is magnifying the ultra-fast jet clumps spewing from a supermassive black hole.

“We couldn’t do studies like these without a university observatory like the Owens Valley Radio Observatory, where we have the time to dedicate a large telescope exclusively to a single program,” said Readhead.

Scientists Use Magnetic Fields To Remotely Stimulate Brain – And Control Body Movements

Scientists have used magnetism to activate tiny groups of cells in the brain, inducing bodily movements that include running, rotating and losing control of the extremities — an achievement that could lead to advances in studying and treating neurological disease.

The technique researchers developed is called magneto-thermal stimulation. It gives neuroscientists a powerful new tool: a remote, minimally invasive way to trigger activity deep inside the brain, turning specific cells on and off to study how these changes affect physiology.

“There is a lot of work being done now to map the neuronal circuits that control behavior and emotions,” says lead researcher Arnd Pralle, PhD, a professor of physics in the University at Buffalo College of Arts and Sciences. “How is the computer of our mind working? The technique we have developed could aid this effort greatly.”

Understanding how the brain works — how different parts of the organ communicate with one another and control behavior — is key to developing therapies for diseases that involve the injury or malfunction of specific sets of neurons. Traumatic brain injuries, Parkinson’s disease, dystonia and peripheral paralysis all fall into this category.

The advances reported by Pralle’s team could also aid scientists seeking to treat ailments such as depression and epilepsy directly through brain stimulation.

The study, which was done on mice, was published Aug. 15 in eLife, an open-source, peer-review journal. Pralle’s team included first authors Rahul Munshi, a UB PhD candidate in physics, and Shahnaz Qadri, PhD, a UB postdoctoral researcher, along with researchers from UB, Philipps University of Marburg in Germany and the Universidad de Santiago de Compostela in Spain.

Magneto-thermal stimulation involves using magnetic nanoparticles to stimulate neurons outfitted with temperature-sensitive ion channels. The brain cells fire when the nanoparticles are heated by an external magnetic field, causing the channels to open.

Targeting highly specific brain regions

In mice, Pralle’s team succeeded in activating three distinct regions of the brain to induce specific motor functions.

Stimulating cells in the motor cortex caused the animals to run, while stimulating cells in the striatum caused the animals to turn around. When the scientists activated a deeper region of the brain, the mice froze, unable to move their extremities.

“Using our method, we can target a very small group of cells, an area about 100 micrometers across, which is about the width of a human hair,” Pralle says.

How magneto-thermal stimulation works

Magneto-thermal stimulation enables researchers to use heated, magnetic nanoparticles to activate individual neurons inside the brain.

Here’s how it works: First, scientists use genetic engineering to introduce a special strand of DNA into targeted neurons, causing these cells to produce a heat-activated ion channel. Then, researchers inject specially crafted magnetic nanoparticles into the same area of the brain. These nanoparticles latch onto the surface of the targeted neurons, forming a thin covering like the skin of an onion.

When an alternating magnetic field is applied to the brain, it causes the nanoparticles’ magnetization to flip rapidly, generating heat that warms the targeted cells. This forces the temperature-sensitive ion channels to open, spurring the neurons to fire.

The particles the researchers used in the new eLife study consisted of a cobalt-ferrite core surrounded by a manganese-ferrite shell.

An advance over other methods, like optogenetics

Pralle has been working to advance magneto-thermal stimulation for about a decade. He previously demonstrated the technique’s utility in activating neurons in a petri dish, and then in controlling the behavior of C. elegans, a tiny nematode.

Pralle says magneto-thermal stimulation has some benefits over other methods of deep-brain stimulation.

One of the best-known techniques, optogenetics, uses light instead of magnetism and heat to activate cells. But optogenetics typically requires implantation of tiny fiber optic cables in the brain, whereas magneto-thermal stimulation is done remotely, which is less invasive, Pralle says. He adds that even after the brains of mice were stimulated several times, targeted neurons showed no signs of damage.

The next step in the research is to use magneto-thermal stimulation to activate — and silence — multiple regions of the brain at the same time in mice. Pralle is working on this project with Massachusetts Institute of Technology researcher Polina Anikeeva, PhD, and Harvard Medical School. The team has $3.5 million in funding from the National Institutes of Health to conduct continuing studies.

The research published in eLife was funded by the National Institute of Mental Health and the Human Frontier Science Program.

Supermassive Black Holes Feed On Cosmic Jellyfish

An Italian-led team of astronomers used the MUSE (Multi-Unit Spectroscopic Explorer) instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile to study how gas can be stripped from galaxies. They focused on extreme examples of jellyfish galaxies in nearby galaxy clusters, named after the remarkable long “tentacles” of material that extend for tens of thousands of light-years beyond their galactic discs .

The tentacles of jellyfish galaxies are produced in galaxy clusters by a process called ram pressure stripping. Their mutual gravitational attraction causes galaxies to fall at high speed into galaxy clusters, where they encounter a hot, dense gas which acts like a powerful wind, forcing tails of gas out of the galaxy’s disc and triggering starbursts within it.

Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the centre, feeding on the surrounding gas [3]. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten.

“This strong link between ram pressure stripping and active black holes was not predicted and has never been reported before,” said team leader Bianca Poggianti from the INAF-Astronomical Observatory of Padova in Italy. “It seems that the central black hole is being fed because some of the gas, rather than being removed, reaches the galaxy centre.” [4]

A long-standing question is why only a small fraction of supermassive black holes at the centres of galaxies are active. Supermassive black holes are present in almost all galaxies, so why are only a few accreting matter and shining brightly? These results reveal a previously unknown mechanism by which the black holes can be fed.

Yara Jaffe, an ESO fellow who contributed to the paper explains the significance: “These MUSE observations suggest a novel mechanism for gas to be funnelled towards the black hole’s neighbourhood. This result is important because it provides a new piece in the puzzle of the poorly understood connections between supermassive black holes and their host galaxies.”

The current observations are part of a much more extensive study of many more jellyfish galaxies that is currently in progress.

“This survey, when completed, will reveal how many, and which, gas-rich galaxies entering clusters go through a period of increased activity at their cores,” concludes Poggianti. “A long-standing puzzle in astronomy has been to understand how galaxies form and change in our expanding and evolving Universe. Jellyfish galaxies are a key to understanding galaxy evolution as they are galaxies caught in the middle of a dramatic transformation.”

Stardust Hitches A Ride On Meteorites More Often Than Previously Thought

 

Even tiny dust particles have stories to tell − especially when they come from outer space. Meteorites contain tiny amounts of what is popularly known as stardust, matter originating from dying stars. Such stardust is part of the raw material from which some 4.6 billion years ago our planets and the meteorite parent bodies, the so-called asteroids, emerged. Peter Hoppe and his team at the Max Planck Institute for Chemistry in Mainz have now discovered that many of the silicate stardust particles in meteorites are much smaller than was previously thought. To date, many of them have therefore probably been overlooked in studies, leading the scientists to believe that the mass of the silicate stardust particles in meteorites is at least twice as large as previously assumed.

The Max Planck scientists obtained the new findings by changing their investigational methods. Using the NanoSIMS ion probe, the researchers in Mainz produced “maps” of thinly sectioned meteorite samples. Such maps show the abundance distribution of specific isotopes in the submicrometre range. The sample is first scanned with a focused ion beam. The particles knocked out of the sample in the process are then analyzed by mass spectrometry. However, even the usual 100-nanometre-wide ion beam was too wide for the latest discovery. “Until now, it was only possible to reliably find stardust grains measuring at least about 200 nanometres. We’ve narrowed the ion beam for our investigations, which means that we’re able to detect many smaller stardust grains,” Peter Hoppe, Group Leader at the MPI for Chemistry, explains. This method was always thought to be too ineffective for sampling, he continues. “Using the conventional, coarser method, you can scan an area ten times greater in the same amount of time.” The researchers were rewarded for their patience and found an unexpectedly high number of “hotspots” with anomalous isotopic abundances in the images of the meteoritic thin sections, indicating the presence of silicate stardust. “Evidently, many of the silicate stardust grains are smaller than was previously thought. With the conventional method, meteoritic stardust grains measuring less than about 200 nanometres have for the most part gone undiscovered,” Peter Hoppe concludes.

Based on the new findings, it is suspected that silicate stardust makes up several percent of the dust in the interstellar proto-mass of our solar system. The discovery by the researchers at the MPI for Chemistry therefore suggests that silicate stardust was a more important component in the birth of our solar system than had been assumed.

A chief component of silicates is oxygen. Unlike silicon carbide stardust, for example, silicate stardust grains cannot be separated from meteorites by chemical methods. Because of this, they remained undetected for a long time. It was only with the help of the NanoSIMS ion probe that the first silicate stardust particle was identified as a “hotspot” in oxygen isotope abundance maps in 2002. The NanoSIMS ion probe is a secondary ion mass spectrometer that is able to measure isotopes on the nanoscale.

Hotspots are areas with unusual isotopic abundances – the fingerprints of the parent stars, which can be clearly identified in the isotope abundance images obtained by measuring the samples. Isotopes of a chemical element have the same number of protons but a different number of neutrons in the nucleus.

Meteoroids are fragments of asteroids (rocky and metal-containing small planets), which circle around the sun as celestial bodies. If meteoroids reach the Earth and survive atmospheric entry, they are called meteorites. A distinction is made between stony, stony-iron and iron meteorites. The Queen Alexandra Range (QUE) 99177, Meteorite Hills (MET) 00426 and Acfer 094 meteorites surveyed by the MPI for Chemistry researchers are a so-called carbonaceous chondrites, which belong to the group of stony meteorites.

UPDATE: NASA Heightened Concerns of Cosmic Ray Influence on Humans and Earth

SpaceX, is a Commercial Resupply Service (CRS-12) mission to the International Space Station  (ISS) currently manifested to be launched on August 13th, 2017. The mission was contracted by NASA and is flown by SpaceX. It will fly the new Dragon capsule. The Falcon 9 rocket’s reusable first stage will attempt a controlled landing on Landing Zone 1 (LZ1) at Cape Canaveral Air Force Station.

Its main mission is to measure dangerous, life-threatening galactic cosmic rays. This project, called the Cosmic-Ray Energetics and Mass investigation (CREAM), features instruments to measure the charges of cosmic rays ranging from hydrogen nuclei up through iron nuclei, over a broad energy range. Researchers report once the ISS astronauts unpack it, the modified balloon-borne device will be placed on the Japanese Exposed Facility for a period of at least three years.

Here is the ‘rub’, a word now popularly use in broadcast news, NASA highlights the very real danger astronauts and cosmonauts will face is the serious consequences from exposure to high-energy galactic cosmic rays, including direct damage to DNA and changes in the biochemistry of cells and tissues.

According to principal investigator Eun-Suk Seo of the University of Maryland Institute for Physical Science and Technology: Seo, says: “People on Earth are protected from these rays by the Earth’s atmosphere and magnetic field”. But what has not been taken into account is the current 14% increase of cosmic ray measurements in just over that last 24 months. Additionally, the quickening rate of Earth’s magnetic field weakening of which both indicators the dangers to humans and Earth are already in-play.

CREAM experiments conducted in six balloon flights at 25-mile (40-kilometer) altitudes over Antarctica have yielded a limited understanding of galactic cosmic rays. More study is needed to better understand the time-linked-means of how and at what pace the GCRs begin to have a measurable effect on our lives and planet in the years to come. The established three-year CREAM mission aboard the space station will significantly expand knowledge of cosmic radiation and what it might take to protect interplanetary travelers in the future.

Military Application:

One final project onboard SpaceX cargo is provided by the U.S. Army Space and Missile Defense Command Army Forces Strategic Command. Chip Hardy, the program manager for the “Kestrel Eye” program, presented an overview of providing real-time information to ground troops regarding enemy location and movement.

Kestrel Eye’s purpose, he said, is to “reduce tactical surprise” and “achieve overmatch at the squad level” by demonstrating operational prototype nanosatellites that make it possible to capture space-based tactical-level intelligence and situational awareness and make synchronized mission-command decisions on the move.